As illustrated in FIG. 1, fuel dispensers 10 are installed in service stations on islands 14. The islands 14 are footprints that are designed to receive a fuel dispenser housing 12. The islands 14 are typically constructed out of cement slabs and have pre-run fuel piping conduits that are run underneath the ground to submersible turbine pumps (not shown) that are coupled to underground storage tanks (not shown) containing fuel. The fuel is pumped from the underground storage tanks to the fuel dispensers 10 via the fuel piping conduit.
As shown in FIG. 1, the fuel piping conduit consists of a main fuel piping conduit 16 that carries fuel underneath each of the fuel dispensers 10. A separate main fuel piping conduit 16 is provided for each grade of fuel stored in underground storage tanks. The main fuel piping conduit 16 is typically double-walled piping to meet regulatory requirements for secondary containment of any leaks that may occur. The main fuel piping conduit 16 contains an inner piping 17 inside that carries the fuel. An interstitial space is formed between the space of the inner piping 17 and the outer piping 18 to provide secondary containment of any leaks that occur in the inner piping 17.
Fuel is directed to individual fuel dispensers 10 by a branch piping conduit 19 that is fluidly coupled to the main fuel piping conduit 16. The branch piping conduit 19 is typically connected to the main fuel piping conduit 16 in a perpendicular fashion, and a fitting 20 is provided at the junction point where the branch piping conduit 19 connects to the main fuel piping conduit 16. The branch fuel piping conduit 19 is then connected to a shear valve 22 located in the island. During installation, field service personnel connects the outlet 24 of the shear valve 22 to the internal fuel piping conduit 26 in the fuel dispenser 10 so that the fuel dispenser 10 has access to fuel pumped from the underground storage tank.
The internal fuel piping conduit 26 is further fitted to fuel dispenser components, such as valves and meters for example, where such fittings introduce the potential for leaks. If a leak occurs in the conduit 26 or at fittings or other fuel dispensing components, regulations require that these leaks are contained. This secondary containment is provided today in the form of a fuel dispenser sump 28 underneath each fuel dispenser 10. The main fuel piping conduit 16 is run into the fuel dispenser sump 28 through fitted connections 30 provided on the fuel dispenser sump 28. Typically, the main fuel piping conduit 16 enters the fuel dispenser sump at connection 29 and the outer piping 16 is terminated thereby leaving on the inner piping 17 inside the fuel dispenser sump 28. Once the inner piping 17 leaves the fuel dispenser sump 28 on the other side, a connection 29 is made to provide double-walled piping 16 until the main fuel piping conduit 16 reaches the next fuel dispenser sump 28.
The branch fuel piping conduit 19 is connected to the main fuel piping conduit 16 via the fitting 20, as previously described. If a leak occurs at the fitting 20 or in the branch fuel piping conduit 19, the leak will be contained in the fuel dispenser sump 28. There are also other points for potential leaks for which the fuel dispenser sump 28 provides secondary containment. One such point is at the fitting 20 that connects the main fuel piping conduit 16 and the branch fuel piping conduit 19, where a potential for a leak exists at the point of the fitting 20. The fitting 20 is not provided with an outer wall or secondary containment that will capture any leaks like that of the main conduit fuel piping 16. The branch fuel piping conduit 19 is also not double-walled piping. Because of the leak potential at the fitting 20 between the main fuel piping conduit 16 and the branch fuel piping conduit 19, and because the branch fuel piping conduit 19 is not double-walled piping, secondary containment contains any leaks that may occur at the fitting 20 and/or in the branch fuel piping conduit 19.
One problem that results from use of a fuel dispenser sump 28 is that the sump will also collect rainwater or other debris that runs into the fuel dispenser 10 from the outside ground. This causes the fuel dispenser sump 28 to fill up even if a leak has not occurred. The fuel dispenser sump 28 is provided with a liquid detection sensor 32 so that service personnel can be alerted when the fuel dispenser sump 28 contains liquid. When significant liquid is detected in the fuel dispenser sump 28 and/or upon the detection of a significant leak and collection of such leak in the fuel dispenser sump 28, the fuel dispenser sump 28 must be emptied by service personnel since it is not known whether the liquid is fuel. Fuel cannot be allowed to overflow the fuel dispenser sump 28. Each time the fuel dispenser sump 28 contains a significant amount of liquid, whether it be leaked fuel, rainwater or other debris, a service visit must be made to empty the fuel dispenser sump 28 thereby causing significant and ongoing servicing expense. The service visit is further complicated by the fact that the fuel dispenser sump 28 is located beneath ground underneath the fuel dispenser 10 and not easily accessed by service personnel for evacuation.
Therefore, there exists a need to provide a fuel dispenser that does not require a fuel dispenser sump below ground to provide secondary containment for leaks. In this manner, the fuel dispenser will easier to service and less costly.